1. Field of the Invention
The present invention relates to generating a network addresses for a node in a computer network. In particular, the present invention relates to generating a network address for a node, the network address is to be securely claimed and defended by the node and one or more other nodes in the computer network.
2. Discussion of the Related Art
In a computer network, it is important to ensure that each network address uniquely identifies a single network node.
U.S. Patent Application Publication 2002/0133607, entitled “Address Mechanisms in Internet Protocol” (the “Nikander Application”) discloses using a one-way coding function to generate an Internet Protocol (IP) address from one or more components specific to a host which claims the IP address. In the Nikander Application, a recipient of a message from the host reconstructs and checks the IP address using the components. The claiming host uses an authentication protocol or a public key cryptographic protocol to establish data integrity on the message, the tie between the components and the address.
U.S. Patent Application Publication 2002/0152384, entitled “Methods and Systems for Unilateral Authentication of Messages” (the “Schelest Application”) discloses deriving an IP Version 6 (IPv6) address hashing the claiming host's public key. In the Schelest Application, a recipient of a message from the claiming host checks the hash of the IPv6 address, and checks a cryptographic signature in the message to verify its data integrity. If both the IPv6 address and the enclosed signature are verified, the recipient accepts the host's claim of ownership over the IPv6 address. “Crypto-Based Identifiers (CBIDs): Concepts and Applications” (the “Montenegro Paper”) by Gabriel Montenegro and Claude Castellucia, ACM Transactions on Information and System Security, Feburary, 2004, reviews the area of cryptographically generated identifiers and their use in establishing authorization to claim the right to use an address by a single host.
U.S. Patent Application Publication 2003/00849293, entitled “Addressing Mechanisms in Mobile IP” (the “Arkko Application”) discloses an owner node delegating the responsibility for its IP address to a second node when the address is generated. In the Arkko Application, the IP address may be cryptographically generated using the methods disclosed in the Nikander or the Schelest Applications. Under the method of the Arkko Application, the owner node obtains a public key of a public/private key pair from the second node, and creates an authorization certificate by signing the obtained public key using the owner node's own private key. The authorization certificate is then provided to the second node, which may then distribute it in any message relating to the owner node's IP address. The second node signs this message, including the authorization certificate, with its private key. A recipient node uses the second node's public key to verify the message and the owner node's public key to verify the authorization certificate. The cryptographic hash of the address verifies the owner node's right to the address and the verified second node's public key in the authorization certificate establishes the second node's right to send messages on behalf of the owner node.
IETF Request for Comment (RFC) 3972, by Aura, March 2005, discloses generating, cryptographically, an IPv6 address and securing the claim of authorization for the IPv6 address in the Neighbor Discovery Protocol (RFC 2461 and RFC 2462). The IPv6 address is generated using both the cryptographic hash of the public key of the owner node and additional information. 64 bits of cryptographic hash serves as the interface identifier of the IPv6 address.
As can be seen from the above, the Nikander and Schelest Applications, the Montenegro Paper, and RFC 3927 relate only to cases in which authorization to use the network address is claimed by a single host. Often, however, it may be necessary to authorize one or most hosts to use an address. Some examples can be found in mobile IPv6 networks and DHCP applications
In a mobile IPv6 network, a mobile node may be reached using a home address on a home network to which the mobile node is assigned. The home address does not change regardless of where the mobile node is on the Internet. When the mobile node is in a remote subnet outside of its home subnet, a “home agent” (e.g., a router on the mobile node's home subnet) forwards messages addressed to the home address of the mobile node to a “care of” address, which is a local address in the remote subnet. To prevent the home address from being claimed by another when the mobile node is away from the home network, the home agent must proxy, or defend, the mobile node's home address. However, if the mobile node generates the home address using a cryptographic identifier tied to its public key, only it can securely defend the home address. The proxy defense by the home agent must be done without security.
Under the IPv6 Neighbor Discovery Protocol, even when a host's address is obtained from a Dynamic Host Configuration Protocol (DHCP) server, the host is still required to claim and defend that address on the network. However, such claim and defense cannot be done securely using cryptographically generated addresses because the address is generated by the DHCP server without the host's public key. Nor can the host sign with its private key a message relating to the address, as the host did not generate the address.
While the Arkko Application discloses an owner node delegating advertising and defense of its address to another party, the solution in the Arkko Application is cumbersome. In the Arkko Application, in addition to using both the owner node's and the delegated node's public keys, an attribute certificate is also required. After generating the address, the attribute certificate is sent by the owner node to the delegated node. As described in the Arkko Application, the solution in the Arkko Application identifies whether the claimant is the owner node or the delegated node. This information can be used by an attacker to infer the location or other information about the owner host.